Missing schemaSetting in case of googlepubsub protocol

[SheheryarAamir]

Describe the bug
When using googlepubsub as protocol using version 1.0.0 generated asynapi(3.0.0) docs does not add schemaSetting under bindings->googlepubsub, which is required for passing asynapi(3.0.0) validation.

Dependencies and versions used
spring-wolf v1.0.0 (CloudStream)

Code example
After some initial investigation I found out that class CloudStreamFunctionChannelsScanner in method buildMessageBinding always map EmptyMessageBinding which is wrong.

Stack trace and error logs
googlepubsub property must have required property schemaSettings

[timonback]

Thank you @SheheryarAamir for the feature request and contribution, it has been published now.

We highly appreciate if you spare some minutes to update the documentation as you have the knowledge of the google pubsub bindings, for example here: https://github.com/springwolf/springwolf.github.io/blob/master/docs/configuration/documenting-bindings.md